Polyvinyl halides plasticized with (1&#39;, 2&#39;-dicarboxyethyl) octadecenoates



Patented Jan. 1, 1952 POLYVINYL HALIDES PLASTICIZED WITH (1',2' DICARBOXYETHYL) ENOATES OCTADEC- Joachim Dazzi, Dayton, Ohio, assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Application May 25, 1950, Serial No. 164,305

(Cl. 260-3L8J 7 Claims.

This invention relates to compositions comprising polymers of vinyl halides and relates more particularly to compositions comprising vinyl chloride polymers plasticized with esters of (1,2-

dicarboxyethyl)octadecenoic acid.

A wide variety of plasticizers has been employed for the purpose of improving the physical properties of vinyl chloride polymers. Particular attention has been given to the improvement of flexibility and heat and light stability of such plasticized compositions. In many instances the improvement in flexibility has been obtainable only by sacrificing other desirable properties of an ideal polyvinyl chloride composition, such as low volatility, color and heat stability, water absorption, etc.

Now I have found that very good flexibility, without sacrifice of temperature stability and low volatility, is imparted to vinyl chloride polymers when there are employed with the polymers certain aralkyl esters of (1',2-dicarboxyethyl) octadecenoic acid. Esters of this type are broadly disclosed in the Clocker Patent U. S. No. 2,188,888, and in the article by Ross, Gebhart and Gerecht, appearing in the Journal of the American Chemical Society, p. 1373 (1946). Briefly, they are obtainable by the addition reaction of maleic'anhydride with oleic acid or its esters and subsequent esterification of the free hydroxy groups. While isomeric products are possible, and the position at which the anhydride residue is attached to the oleic compound is not known, the reaction of oleic acid or of an alkyl oleate with maleic anhydride proceeds probably according to the scheme:

wherein a: is a whole number between 5 and 8 and R is a member of the group consisting of hydrogen, alkyl radicals of from 1 to 4 carbon atoms and saturated aralkyl radicals of from 7 to 8 carbon atoms.

Esteriflcation of the resulting adduct with a saturated aralkyl alcohol of from 7 to 8 carbon atoms, e. g., benzyl alcohol, fi-phenylethanol or 0-, p-, or m-methylbenzyl alcohol yields the trialkyl ester which probably has the structure:

(ma n-1), li--(ll:(ll(( ll2)1:\-.v R

ncook I im-(00W in which R is as defined above and R is a saturated aralkyl radical of from"? to 8 carbon atoms and a: is a whole number between 5 and 8.

Because of uncertainty concerning the position at which the maleic residue is attached to the oleic group, the present esters will be hereinafter referred to without stipulating the position of the fl',2'-dicarboxyethyl) group.

As examples of compounds having the above general formula may be mentioned tribenzyl 1 ,2'-dicarboxyethyl) octadecenoate, the alkyl [1,2' bisicarbobenzyloxy)ethylloctadecenoates in which the alkyl group has from 1 to 4 carbon atoms, tris(phenethyl) (l',2-dicarboxyethyl) octadecenoate, the alkyl [1,2 -bis(phenethoxy) ethylloctadecenoates in which the alkyl group has from 1 to 4 carbon atoms, the ar-methylbenzyl (1',2'-dicarboxyethyl) octadecenoates such as tri-p-methylbenzyl 1',2'-dicarboxyethyl) octadecenoate.

I have found that in order to obtain stable, light-colored adducts certain reaction conditions must be adhered to carefully. For example, while the addition of maleic anhydride to oleic acid takes place under varying reaction conditions, useful plasticizers for the present purpose are best prepared by conducting the reaction for comparatively short periods of time, say, from 1 hour to 8 hours, at relatively low temperatures, i. e., at temperatures not exceeding the decomposition point of the initial reactants. I have found also that great care should be used in isolating the desired products. After the esteriflcation, I preferably fractionate the crude reaction mixture under a very low vacuum, i. e., at vacuums of 1 mm. of mercury or less. Fractionation at such low pressures minimizes the formation of dark colored impurities whose presence in the finished product leads to poor plasticized compositions. Dark colored impurities are also avoided by preparing the present (1,2'-dicarboxyethyl) octadecenoates according to the procedure described in my copending application, Serial No. 144,393, filed February 15, 1950.

The present aralkyl (1',2'-dicarboxyethyl)octadecenoates are valuable plasticizers for polyvinyl chloride and copolymers of at least '70 per cent by weight of vinyl chloride and up to, 30

per cent by weight or an unsaturated monomer copolymerized therewith, for example vinyl acetate, vinylidene chloride, etc.

Adducts or acyclic oleflnic acids and longchained unsaturated acids have been hitherto generally suggested for use as softening agents. I have now found, however, that aralkyl (1,2'- dicarboalkoxy)octadecenoates in which the are!- kyl radicals have from 7 to 8 carbon atoms are of outstanding value as plasticizers, these esters serving not only to soften vinyl chloride polymers, but also to impart simultaneously a high degree of low temperature flexibility, very good temperature stability and great mechanical strength to these polymers. While many of the esters encompassed by the Clocker patent referred to above are incompatible with polymers and copolymers of vinyl chloride and do not give continuous, homogeneous compositions, esters of (1 ,2'-dicarboxyethyl) octadecenoic acid with aralkyl alcohols of from '7 to 8 carbon atoms are compatible with vinyl chloride polymers and show no exudation of plasticizer even at plasticizer content of up to 50 per cent. Although the quantity of plasticizer will depend upon the particular polymer to be plasticized and upon its molecular weight, it is generally found that compositions having from per cent to 50 per cent by weight of plasticizer will, in most cases, be satisfactory for general utility. The good flexibility of the plasticized compositions increases with increasing plasticizer concentration.

In evaluating plasticizer efiiciency use is made of the following empirical testing procedures:

Compatibility-Visual inspection of the plasticized composition is employed, incompatibility of the plasticizer with the polymer being demonstrated by cloudiness and exudation oi the plasticizer.

Hardness.-A standard instrument made by the Shore Instrument Company is used for this determination and expresses the hardness in units from 1 to 100. The hardness of a composition is judged by its resistance to the penetration of a standard needle applied to the composition under a standard load for a standard length of time.

Low temperature flexibility-Low temperature flexibility is one of the most important properties of elastomeric vinyl compositions. While many plasticizers will produce flexible compositions at room temperature the flexibility of these compositions at low temperatures may vary considerably, i. e., plasticized polyvinyl chloride compositions that are flexible at room temperature often become very brittle and useless at low temperatures. Low temperature flexibility tests herein employed are according to the Clash-Berg method. This method determines the torsional flexibility of a plastic at various temperatures. The temperature at which the vinyl composition exhibits an arbitrarily established minimum flexibility is defined as the low temperature flexibility of the composition. This value may also be defined as the lower temperature limit of the plasticized compositions usefulness as an elastomer.

Volatility-Just as a decrease in low temperature often results in decreased flexibility of a plasticized polymer composition so does a decrease in plasticizer concentration when caused by volatilization of the plasticizer. Hence. plasticizers which are readily volatilized from the plasticized composition as a result of aging or heating are inefllcient because upon volatilization Example Sixty parts 01' polyvinyl chloride and 40 parts by weight of the tribenzyl ester of (l',2'-dicarboxyethyl) octadecenoic acid are mixed on a rolling mill to a homogeneous blend. During the milling there was observed substantially no fuming and discoloration. A molded sheet of the mixture was clear and transparent and substantially colorless. Testing of the molded sheet for low temperature flexibility, according to the testing procedure described above, gave a value 0! minus 16 C. which value denotes extremely good low temperature properties. Tests on the volatility characteristics of the plastlcized composition gave a value of 0.6 per cent which showed very good retention of plasticizer and indicated good temperature characteristics of the composition. The plasticized material had a hardness of 82 before the volatility test and a hardness of 82 after the volatility test. When subjected to heat at a temperature of 325 F. for a period of 30 minutes the clarity and color or the molded product were substantially unchanged.

Instead of the ester employed in the example above, other esters of (l',2'-dicarboxyethyl)octadecenoic acid with saturated aralkyl alcohols of from '7 to 8 carbon atoms gave similarly valuable plasticized polyvinyl chloride compositions. Thus, by employing 40 parts by weight of the tris(phenethyl), or the tris(o-methylbenzyl) ester of (l',2'-dicarboxyethyl) octadecenoic acid or ethyl [1,2' bis(carbobenzyloxy)ethylloctadecenoate with 60 parts by weight of polyvinyl chloride, or with 60 parts by weight of a vinyl chloride-vinyl acetate copolymer known to the trade as Vinylite there are obtained clear, colorless compositions of very good flexibility and stability.

While the above example shows only compositions in which the ratio of plasticizer to polymer content is 40:60, this ratio being employed in order to get comparable efllciencles, the content 01' ester to polyvinyl chloride may be widely-varied, depending upon the properties desired in the final product. For many purposes a plasticizer content of, say, from only 10 per cent to 20 per cent is preferred. The present esters are compatible with polyvinyl chloride over wide ranges of concentrations, up to per cent of esters based on the total weight of the plasticized composition yielding desirable products.

Although the invention has been described particularly with reference to the use of the present aralkyl esters of (1',2'-dicarboxyethyl)octadecenoic acid as plasticizers for polvinyl chloride, these esters are advantageously employed also as plasticizers for copolymers of vinyl chloride, for example, the copolymers of vinyl chloride with vinyl acetate, vinylidene chloride, etc. Preferably, such copolymers have a high vinyl chloride content, i. e., a vinyl chloride content of at least '70 per cent by weight of vinyl chloride and up to 30 per cent by weight of the copolymerizable monomer.

The plasticized polyvinyl halide compositions of the present invention have good thermal stability; however, for many purposes it may be ad.- vantageous to use known stabilizers in the plasti- 7 cized compositions. Inasmuch as the present esters are substantially unreactive with the commercially available heat and light stabilizers which are commonly employed with polyvinyl chloride or copolymers thereof, the presence of such materials in the plasticized materials does not impair the valuable properties of the present esters. The present esters are of general utility in softening vinyl chloride polymers. They may be used as the only plasticizing component in a compounded vinyl chloride polymer or they may be used in conjunction with other plasticizers.

What I claim is:

1. A resinous composition comprising a vinyl chloride polymer plasticized with an ester selected from the class consisting of tris-aralkyl (1,2- dicarboxyethyl)octadecenoates and bis-aralkyl mono-alkyl (1' ,2 -dicarboxyethyl) octadecenoates in which each aralkyl radical has from 7 to 8 carbon atoms and each aikyl radical has from 1 to 4 carbon atoms.

2. A resinous composition comprisin polyvinyl chloride plasticized with an ester selected from the class consisting of tris-aralkyl (1',2'-dicarboxyethyDoctadecenoates and bis-aralkyl monoalkyl (1',2' dicarboxyethyl)octadecenoates in which each aralkyl radical has from 7 to 8 carbon atoms and each alkyl radical has from 1 to 4 carbon atoms.

3. A resinous composition comprising polyvinyl chloride plasticized with an ester selected from the class consisting of trisaralkyl (1,2'-dicarboxyethyDoctadecenoates and bis-aralkyl monoalkyl (1,2 dicarboxyethyl)octadecenoates in which each alkyl radical has from 1 to 4 carbon atoms and each aralkyl radical has from 7 to 8 carbon atoms, said ester being from 5 to 50 per cent of the weight of the composition.

4. A resinous composition comprising a copolymer or at least 70 per cent by weight of vinyl chloride and up to 30 per cent by weight of an unsaturated monomer copolymerizable therewith, said copolymer being plasticized with an ester selected from the class consisting of tris-aralkyl (1',2 -dicarboxyethyl)octadecenoates and bisaralkyl mono-alkyl (1 ,2 -dicarboxyethyl) octadecenoates in which each aralkyl radical has from 7 to 8 carbon atoms and each alkyl radical has from 1 to 4 carbon atoms.

5. A resinous composition comprising a copolymer of at least 70 per cent by weight of vinyl chloride and up to 30 per cent by weight of an unsaturated monomer copolymerizable therewith, said copolymer being plasticized with an ester selected from the class consisting of tris-aralkyl (1',2' -dicarboxyethyl)octadecenoates and hisaralkyl mono-alkyl (1',2'-dicarboxyethyl)octadecenoates in which each alkyl radical has from 1 to 4 carbon atoms and each aralkyl radical has from 7 to 8 carbon atoms, and said ester being from 5 to 50 per cent of the weight of the composition.

6. A resinous composition comprising polyvinyl chloride plasticized with an ester selected from the class consisting of tribenzyl (1',2'-dicarboxyethyli'octadecenoate and dibenzyl mono-alkyl (1 ',2 -dicarboxyethyl) octadecenoates in which each alkyl radical has from 1 to 4 carbon atoms, said ester being from 5 to 50 per cent of the weight of the composition.

'7. A resinous composition comprising polyvinyl chloride plasticized with the tribenzyl ester of .(1,2'-dicarboxyethyl)octadecenoic acid, said ester being from 5 to 50 per cent of the weight of the composition.

JOACHIM DAZZI.

No references cited. 

1. A RESINOUS COMPOSITION COMPRISING A VINYL CHLORIDE POLYMER PLASTICIZED WITH AN ESTER SELECTED FROM THE CLASS CONSISTING OF TRIS-ARALKYL (1'',2''DICARBOXYETHYL) OCTADECENOATES AND BIS-ARALKYL MONO-ALKYL (1'',2''-DICARBOXYETHYL) OCTADECENOATES IN WHICH EACH ARALKYL RADICAL HAS FROM 7 TO 8 CARBON ATOMS AND EACH ALKYL RADICAL HAS FROM 1 TO 4 CARBON ATOMS. 